What are the intended default margins for Print Page (section 18.1)

[emanlove]

An observation about Section 18.1 Print Page with the w3c WebDriver spec. With the remote end steps, it's stated that the default page width and height (steps 10 & 11) are 21.59 and 27.94 both without units. Later within step 23 we see the units of “cm” assigned to the width, height and margin properties. Together this makes sense as that would put the default page size to a US standard “Letter” size page. But looking at the default values for the top, bottom, left, right margins (steps 14, 15, 16, 17 respectively) these are all set to 1 without units. Again the assumption is that those are all then 1 cm margins. My observation and what I am asking is, there is a “commonly used standard” of 1 inch for the margin within the US. To me it almost looks as if these default Letter pages are trying to set the default margin to one inch and not to the equivalent cm margin.